1. Field of the Invention
The invention relates to an erase method of a flash memory, and more particularly to an erase method of a flash memory for quickly determining a blank sector.
2. Description of the Related Art
Specific data is written into a flash memory by a program mechanism and an erase mechanism for data storage. In general, the write algorithm and the erase algorithm will induce different issues according to various command sheets, e.g. over erase. Taking an erase procedure as an example, the erase procedure mainly comprises a pre-program step, an erase step and a post-program step, to ensure that each memory cell is at a logic level “1” after the erase procedure is performed. When the erase procedure and the program procedure is repeatedly performed, the execution time of the erase procedure will gradually increase with the increase in the number of writing times, wherein the post-program step of repairing the over-erased memory cells will occupy most of the execution time in the erase procedure. When a sudden event occurs, such as when a shutdown condition suddenly occurs, the post-program may be interrupted, which causes the post-program step of the flash memory to not be performed completely. Thus, it needs more time to verify the flash memory, and to find a blank sector, so as to avoid any over-erased memory cell in the sector that will cause false readings.